Systems and methods for remote buoyancy control

ABSTRACT

A system for controlling the buoyancy of a remotely operated vehicle. The system includes buoyancy tanks, storage tanks, pressure sensors, gyroscopes, a control unit, and transporting and conducting means to couple all the elements. The system autonomously adjusts the depth of all or part of the remotely operated vehicle based at least in part on the pressure readings and the orientation of the remotely operated vehicle. The system is designed to reach the depths of the ocean floor either by a high pressure encasement, or by adjusting the internal pressure of the buoyancy tanks to withstand the ambient pressure exerted by the column of water. The system is entirely closed, meaning that the buoyancy can be adjusted simply by moving gas between a storage tank to a buoyancy tank. The system can finely control total depth, roll, pitch, and yaw of the remotely operated vehicle.

FIELD OF THE INVENTION

This invention relates generally to buoyancy control, and, morespecifically, to systems and methods for remote buoyancy control.

BACKGROUND OF THE INVENTION

Remotely operated vehicles are often used to conduct activities at greatdepths, such as on the ocean floor. The environment on the ocean flooris includes darkness, extreme high and low temperatures, and extremelyhigh pressures. It is necessary to control the buoyancy of theseremotely operated vehicles so that they do not merely drop to the oceanfloor and can instead be used to conduct maneuvers, such as picking upor moving objects. The most commonly used current technology foradjusting buoyancy of these remotely operated vehicles consists of foamblocks, which allow only a particular depth to be reached andmaintained, and which often break under the pressure of the water columnabove the remotely operated vehicle. Moreover, these foam blocks onlyallow for the rough adjustment up or down of the remotely operatedvehicle. Another technology in less common use is the replacement of gascanisters on the remotely operated vehicle. When the remotely operatedvehicle needs to descend, it releases gases from its buoyancy chambersand begins to fall. When it needs to ascend, the remotely operatedvehicle must acquire new gas, a task which is difficult at depth. Thisrequires the pre-placement of gas canisters on the ocean floor, orrequires a tether to the surface for gas to be flowed to the remotelyoperated vehicle, both of which are inefficient and expensiveoperations. In the present invention, the needs for foam blocks,replacement canisters, and tethers are obviated.

SUMMARY

The present invention is an autonomous, closed-loop system that storesand releases gases to adjust the buoyancy of the remotely operatedvehicle, eliminating the waste found in existing systems. Furthermore,the present invention allows the remotely operated vehicle to make moreprecise movements than existing systems allow. The system is set up suchthat fine alterations of gas volumes in a closed-loop system may beautonomously controlled, moving the same gas from storage tanks tobuoyancy tanks and back, providing an autonomous buoyancy control systemthat can change the depth, roll, pitch, and yaw of the remotely operatedvehicle. Moreover, the system autonomously adjusts the pressure of thebuoyancy tanks to be within a pre-designated ratio to the ambientpressure, up to the pressure at the ocean floor, which is approximately16,000 pounds per square inch. This allows the system to be open to theenvironment, partially accounting for the fine movements and adjustmentsfacilitated by the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are described in detail below withreference to the following drawings:

FIG. 1 is a representative view of an exemplary arrangement of thebuoyancy control system.

FIG. 2 is an example of a control arrangement.

DETAILED DESCRIPTION

The buoyancy control system provides a system for precisely controllingthe depth, roll, pitch, and yaw of remotely operated vehicles. Thebuoyancy control system consists essentially of at least one buoyancytank, at least one pressurized storage tank coupled with the at leastone buoyancy tank, and at least one control arrangement, the at leastone control arrangement coupled with the at least one pressurizedstorage tank. In the present embodiment, the system forms a closed loopsuch that no gases are released.

FIG. 1 shows the buoyancy control system, 1, on top of and coupled withthe remotely operated vehicle, 2. The buoyancy control system is a meansfor controlling any of the depth, roll, pitch, or yaw of a remotelyoperated vehicle. In the present embodiment, the buoyancy control systemis attachable to existing remotely operated vehicles. This is anexemplary embodiment, and it should not be construed as limiting. Inother embodiments, the buoyancy control system is built into theremotely operated vehicle. In other embodiments, the buoyancy controlsystem is attached to the bottom of the remotely operated vehicle. Inother embodiments, the buoyancy control system is attached to theremotely operated vehicle in combination with other buoyancy controlsystems. In other embodiments, the buoyancy control system is attachedto a side of the remotely operated vehicle.

The buoyancy control system is comprised essentially of a buoyancy tank,3. In one embodiment, the buoyancy tank is a means for increasing thevolume of gas in the buoyancy control system, which results in increasedbuoyancy. In another embodiment, it is a means for changing the locationof a gas. In yet another embodiment, it is a means for changing thevolume of a gas in a discrete location of the buoyancy control system.FIG. 1 shows an embodiment with three buoyancy tanks, a left tank 3, amiddle tank 4, and a right tank, 5. This is an exemplary embodiment andshould not be construed as limiting. In another embodiment, the buoyancycontrol system may have only one buoyancy tank in any location in thebuoyancy control system. In another embodiment, the buoyancy controlsystem may have two or more buoyancy tanks, in any number of locationcombinations. The buoyancy tank can be either rigid or flexible. In someembodiments, the buoyancy tank may be a standard gas cylinder. In otherembodiments, the buoyancy tank may be a pressure vessel. In furtherembodiments, the buoyancy tank may be a high pressure cylinder. In someembodiments, the buoyancy tank may be a pressure cylinder certified tointernational or national standards.

In the present embodiment, the buoyancy control system comprises astorage tank, 6. In one embodiment, a storage tank is a means forcompressing a gas in the buoyancy control system. In a furtherembodiment, a storage tank is a means for reducing the volume of a gasin the buoyancy control system, which results in decreased buoyancy. Inanother embodiment, it is a means for changing the location of a gas. Inyet another embodiment, it is a means for changing the volume of a gasin a discrete location of the buoyancy control system. FIG. 1 shows anembodiment with a left storage tank, 6, and a right storage tank, 7.This is an exemplary embodiment and should not be construed as limiting.In another embodiment, the buoyancy control system may have only onestorage tank in any location in the buoyancy control system. In anotherembodiment, the buoyancy control system may have two or more storagetanks, in any number of location combinations. The storage tank can beeither rigid or flexible. In some embodiments, the storage tank may be astandard gas cylinder. In other embodiments, the storage tank may be apressure vessel. In further embodiments, the storage tank may be a highpressure cylinder. In some embodiments, the storage tank may be apressure cylinder certified to international or national standards. Insome embodiments, the storage tank is a pressurized storage tank.

In the present embodiment, the buoyancy control system comprises acontrol unit, 8. The control unit is a means for controlling thebuoyancy control system. Moreover, it is a means for determining apressure, a pressure differential, or an orientation of the buoyancycontrol system. It is also a means for adjusting a flow of a gas bycontrolling a pump or a valve. In the present embodiment, the controlunit is part of a control arrangement, further comprising at least onepressure sensor, 9. A pressure sensor is a means for detecting apressure of a gas or a liquid. This is an exemplary embodiment andshould not be construed as limiting. In another embodiment, the controlarrangement has no pressure sensors. In another embodiment, the controlarrangement comprises a single pressure sensor. In further embodiments,the control arrangement comprises a plurality of pressure sensorslocated in or around the buoyancy tanks, the walls of the buoyancycontrol system, and the storage tanks. One skilled in the art wouldunderstand that the pressure sensors may be any device which measurespressure, force, or density, including but not limited to load cells,transducers, strain gauges, manometers, and piezoelectric sensors.

In one embodiment, the control arrangement comprises a pressure sensorcoupled with the control unit, which contains circuitry for determininga pressure at least partially based on a reading of the pressure sensor.In a further embodiment, the control arrangement comprises a firstpressure sensor and a second pressure sensor, both of which are coupledto the control unit, which contains circuitry or other means forcomparing a pressure reading from the first pressure sensor against apressure reading from the second pressure sensor. In another embodiment,the control arrangement comprises a plurality of pressure sensorscoupled to the control unit. The control unit contains circuitry fordetermining the pressures at each pressure sensor based at leastpartially on a reading from each sensor, and comparing the pressures ateach pressure sensor to one another. In a further embodiment, thecontrol unit contains circuitry for comparing a reading of a pressuresensor to at least one preset pressure threshold.

In the present embodiment, the control arrangement comprises at leastone gyroscope, 10. A gyroscope is a means for detecting an orientationof the buoyancy control system, the orientation consisting of the roll,pitch, and yaw of the buoyancy control system. This is an exemplaryembodiment and should not be construed as limiting. In the presentembodiment, the gyroscope is coupled with the control unit, whichcontains circuitry for determining an orientation at least partiallybased on a reading of the at least one gyroscope. In another embodiment,the control arrangement comprises a plurality of gyroscopes. The controlunit contains circuitry for comparing the readings of each gyroscope anddetermining an orientation at least partially based on a reading of theat least one gyroscope. One skilled in the art would understand that thegyroscope can be any of a number of known gyroscope technologies,including but not limited to a Micro Electro-Mechanical System, a fiberoptic gyroscope, a hemispherical resonator gyroscope, a vibratingstructure gyroscope, a dynamically tuned gyroscope, a London momentgyroscope, and an accelerometer or plurality of accelerometers.

FIG. 2 depicts an exemplary control arrangement. In the presentembodiment, the control arrangement comprises at least one pressuresensor, circuitry for determining a pressure at least partially based ona reading of the at least one pressure sensor, at least one gyroscope,circuitry for determining an orientation at least partially based on areading of the at least one gyroscope, and circuitry for adjusting aflow of a gas at least partially based on a pressure and the orientationof the buoyancy control system. In another embodiment, the controlarrangement comprises at least a first pressure sensor, at least asecond pressure sensor, circuitry for determining a comparative pressurebetween the first pressure sensor and the second pressure sensor, atleast one gyroscope, circuitry for determining an orientation at leastpartially based on a reading of the at least one gyroscope, andcircuitry for adjusting a flow of a gas at least partially based on thecomparative pressure and the orientation of the buoyancy control system.In a further embodiment, the control arrangement comprises circuitry foradjusting a flow of a gas at least partially based on the comparativepressure and the orientation of the buoyancy control system, wherein theadjusting the flow of the gas alters the volume of gas in the at leastone buoyancy tank.

Returning now to FIG. 1, the present embodiment of the buoyancy controlsystem further comprises a gas pump, 11. A pump is a means for movingthe gas through the buoyancy control system. In the present embodiment,the pump is triggered by the control unit in the control arrangement,based at least partially on the pressure or orientation determinationfrom the control unit circuitry. In another embodiment, a pump may bereplaced with a valve or a plurality of valves. In a further embodiment,valves may be one way valves. In that particular embodiment, one wayvalves would support a single flow direction, allowing gas to move inonly one direction through the entire closed loop system. In oneembodiment, this may enable a passive system, in which gas moved from ahigher pressure tank into a lower pressure tank. Conversely, a one wayvalve may enable a passive system that prevents gas from moving from ahigher pressure tank to a lower pressure tank. In another embodiment,valves may be two way valves. In another embodiment, a pump may be usedin conjunction with a valve in order to control and move the gas in thebuoyancy control system. In another embodiment, a pump may be usedwithout a valve, relying only on the structure and function of the pumpto move and prevent movement of gas in the system. In one embodiment,there may be a plurality of pumps. In one embodiment, there may be aplurality of valves.

FIG. 1 also depicts a casing, 12, around the buoyancy control system. Inthe present embodiment, the casing is designed to withstand pressures onthe ocean floor, up to 16,000 pounds per square inch. This is anexemplary embodiment and should not be construed as limiting. In anotherembodiment, the buoyancy control system is designed without a highpressure casing. In this embodiment, the control arrangement includes afirst pressure sensor to measure an external pressure, such as the waterpressure on the external surfaces of the buoyancy control system, asecond pressure sensor to measure an internal pressure, such as thepressure inside a buoyancy tank, circuitry for determining a comparativepressure between the first pressure sensor and the second pressuresensor, and circuitry for adjusting the internal pressure based on thecomparative pressure determination. In this embodiment, the control unitautonomously adjusts the pressure in the buoyancy tanks to be at or nearthe pressure exerted by the column of water. This allows the buoyancytanks to be uncovered, which allows for more accurate and fineadjustments in the buoyancy of the remotely operated vehicle.Furthermore, it allows for a controlled rate of descent or ascent of theremotely operated vehicle.

Not depicted are the various transporting means in the presentembodiment. Transporting means are tubes or hoses are connecting theelements of the buoyancy control system and moving gases between thoseelements. In the present embodiment, transporting means may be used tocouple a storage tank with a buoyancy tank. In another embodiment,transporting means may be used to couple a first storage tank with asecond storage tank. In another embodiment, transporting means may beused to couple a first buoyancy tank with a second buoyancy tank.Transporting means may be rigid or flexible. Transporting means may beoff-the-shelf transporting means. Alternatively, transporting means maybe high pressure transporting means. Transporting means may be certifiedto national or international standards. One skilled in the art wouldunderstand that the exact configuration of tubes and hoses willnecessarily depend on the particular embodiment employed.

Also not depicted are the various conducting means in the presentembodiment. In the present embodiment, conducting means may be used tocarry signals between a control arrangement and the tanks. In anotherembodiment, conducting means may be used to carry signals between acontrol arrangement and pumps. In another embodiment, conducting meansmay be used to carry signals between a control arrangement and valves.In another embodiment, conducting means may be used to carry signalsbetween a pressure sensor and a control unit. In another embodiment,conducting means may be used to carry signals between a gyroscope and acontrol unit. One skilled in the art would understand that conductingmeans includes but is not limited to metallic and non-metallic wires,fiber optics, and wireless transmission signals.

In an exemplary embodiment, the buoyancy control system is comprised ofa buoyancy tank, a storage tank coupled to the buoyancy tank, and acontrol arrangement coupled to the storage tank. In a furtherembodiment, the control arrangement contains a pressure sensor. When thecontrol unit determines that the ambient pressure is above a threshold,the control unit allows some gas to move from the storage tank to thebuoyancy tank, providing more buoyancy and lifting the remotely operatedvehicle. When the control unit detects that the ambient pressure isbelow a threshold, the control unit allows some gas to move from thebuoyancy tank to the storage tank, providing less buoyancy and droppingthe remotely operated vehicle. One skilled in the art would understandthat the gas in the storage tank is under extreme pressure, reducing thevolume and allowing the decrease in buoyancy. This is an aspect thatmakes the present invention unique, because it is, in part, what enablesa closed-loop system.

In another exemplary embodiment, the buoyancy control system iscomprised of a buoyancy tank, a storage tank coupled to the buoyancytank, and a control arrangement coupled to the storage tank. In afurther embodiment, the control arrangement contains a plurality ofpressure sensors. For example, the buoyancy control system may have apressure sensor to measure ambient pressure and a pressure sensor tomeasure the pressure in a buoyancy tank. In this embodiment, the controlunit contains circuitry for comparing a pressure reading from the firstpressure sensor against a pressure reading from the second pressuresensor. The control unit then allows gas to move in or out of thebuoyancy tank to maintain a particular pressure differential. Thisembodiment is what allows the buoyancy control system to function absentthe high pressure casing, because it can autonomously adjust thepressure in the buoyancy tanks to withstand the pressure exerted by thecolumn of water above the remotely operated vehicle to which thebuoyancy control system is coupled.

In another exemplary embodiment, the buoyancy control system iscomprised of a plurality of buoyancy tanks, a storage tank coupled withthe plurality of buoyancy tanks, and a control arrangement coupled withthe pressurized storage tank. In a further embodiment, the controlarrangement contains a gyroscope. In this embodiment, the control unitdetermines an orientation of the buoyancy control system, and thereforethe remotely operated vehicle, based at least partially on the readingof the gyroscope. Based at least partially on that orientationdetermination, the control unit then allows gas to move in or out of theplurality of buoyancy tanks to alter the orientation. One skilled in theart would understand that this embodiment allows the buoyancy controlsystem to control the roll, pitch, and yaw, as well as the depth, of theremotely operated vehicle.

Those skilled in the art will appreciate that the foregoing specificexemplary processes and/or devices and/or technologies arerepresentative of more general processes and/or devices and/ortechnologies taught elsewhere herein, such as in the claims filedherewith and/or elsewhere in the present application.

The claims, description, and drawings of this application may describeone or more of the instant technologies in operational/functionallanguage, for example as a set of operations to be performed by acomputer. Such operational/functional description in most instanceswould be understood by one skilled the art as specifically-configuredhardware (e.g., because a general purpose computer in effect becomes aspecial purpose computer once it is programmed to perform particularfunctions pursuant to instructions from program software).

What is claimed is:
 1. A buoyancy control system comprising: at leastone buoyancy tank; at least one pressurized storage tank coupled withthe at least one buoyancy tank; and at least one control arrangement,the at least one control arrangement coupled with the at least onepressurized storage tank.
 2. The buoyancy control system of claim 1,wherein the system forms a closed loop such that no gas is released. 3.The buoyancy control system of claim 1, wherein the at least one controlarrangement comprises: at least one pressure sensor; and circuitry fordetermining a pressure at least partially based on a reading of the atleast one pressure sensor.
 4. The buoyancy control system of claim 2,wherein the at least one control arrangement comprises: at least a firstpressure sensor; at least a second pressure sensor; and circuitry forcomparing a pressure reading from the first pressure sensor against apressure reading from the second pressure sensor.
 5. The buoyancycontrol system of claim 1, wherein the at least one control arrangementcomprises: at least one gyroscope; and circuitry for determining anorientation at least partially based on a reading of the at least onegyroscope.
 6. The buoyancy control system of claim 1, wherein the atleast one control arrangement comprises: at least one pressure sensor;circuitry for determining a pressure at least partially based on areading of the at least one pressure sensor; at least one gyroscope;circuitry for determining an orientation at least partially based on areading of the at least one gyroscope; and circuitry for adjusting aflow of a gas at least partially based on a pressure and the orientationof the buoyancy control system.
 7. The buoyancy control system of claim1, wherein the at least one control arrangement comprises: at least afirst pressure sensor, the first pressure sensor situated to measure anexternal pressure; at least a second pressure sensor, the secondpressure sensor situated to measure an internal pressure; circuitry fordetermining a comparative pressure between the first pressure sensor andthe second pressure sensor; and circuitry for adjusting the internalpressure based on the comparative pressure determination.
 8. Thebuoyancy control system of claim 1, wherein the at least one controlarrangement comprises: at least a first pressure sensor; at least asecond pressure sensor; circuitry for determining a comparative pressurebetween the first pressure sensor and the second pressure sensor; atleast one gyroscope; circuitry for determining an orientation at leastpartially based on a reading of the at least one gyroscope; andcircuitry for adjusting a flow of a gas at least partially based on thecomparative pressure and the orientation of the buoyancy control system.9. The buoyancy control system of claim 1, wherein the at least onecontrol arrangement comprises: at least a first pressure sensor; atleast a second pressure sensor; circuitry for determining a comparativepressure between the first pressure sensor and the second pressuresensor; at least one gyroscope; circuitry for determining an orientationat least partially based on a reading of the at least one gyroscope; andcircuitry for adjusting a flow of a gas at least partially based on thecomparative pressure and the orientation of the buoyancy control system,wherein the adjusting the flow of the gas alters the volume of gas inthe at least one buoyancy tank.
 10. A buoyancy control systemcomprising: a plurality of buoyancy tanks; at least one pressurizedstorage tank coupled with the plurality of buoyancy tanks; and at leastone control arrangement, the at least one control arrangement coupledwith the at least one pressurized storage tank.
 11. The buoyancy controlsystem of claim 10, wherein the system forms a closed loop such that nogases are released.
 12. The buoyancy control system of claim 10, whereinthe at least one control arrangement comprises: at least one pressuresensor; and circuitry for determining a pressure at least partiallybased on a reading of the at least one pressure sensor.
 13. The buoyancycontrol system of claim 10, wherein the at least one control arrangementcomprises: at least a first pressure sensor; at least a second pressuresensor; and circuitry for comparing a pressure reading from the firstpressure sensor against a pressure reading from the second pressuresensor.
 14. The buoyancy control system of claim 10, wherein the atleast one control arrangement comprises: at least one gyroscope; andcircuitry for determining an orientation at least partially based on areading of the at least one gyroscope.
 15. The buoyancy control systemof claim 10, wherein the at least one control arrangement comprises: atleast one pressure sensor; circuitry for determining a pressure at leastpartially based on a reading of the at least one pressure sensor; atleast one gyroscope; circuitry for determining an orientation at leastpartially based on a reading of the at least one gyroscope; andcircuitry for adjusting a flow of a gas at least partially based on apressure and the orientation of the buoyancy control system.
 16. Thebuoyancy control system of claim 10, wherein the at least one controlarrangement comprises: at least a first pressure sensor, the firstpressure sensor situated to measure an external pressure; at least asecond pressure sensor, the second pressure sensor situated to measurean internal pressure; circuitry for determining a comparative pressurebetween the first pressure sensor and the second pressure sensor; andcircuitry for adjusting the internal pressure based on the comparativepressure determination.
 17. The buoyancy control system of claim 10,wherein the at least one control arrangement comprises: at least a firstpressure sensor; at least a second pressure sensor; circuitry fordetermining a comparative pressure between the first pressure sensor andthe second pressure sensor; at least one gyroscope; circuitry fordetermining an orientation at least partially based on a reading of theat least one gyroscope; and circuitry for adjusting a flow of a gas atleast partially based on the comparative pressure and the orientation ofthe buoyancy control system.
 18. The buoyancy control system of claim10, wherein the at least one control arrangement comprises: at least afirst pressure sensor; at least a second pressure sensor; circuitry fordetermining a comparative pressure between the first pressure sensor andthe second pressure sensor; at least one gyroscope; circuitry fordetermining an orientation at least partially based on a reading of theat least one gyroscope; and circuitry for adjusting a flow of a gas atleast partially based on the comparative pressure and the orientation ofthe buoyancy control system, wherein the adjusting the flow of the gasalters the volume of gas in the plurality of buoyancy tanks.
 19. Abuoyancy control system comprising: a plurality of buoyancy tanks; atleast one pressurized storage tank coupled with the plurality ofbuoyancy tanks; and at least one control arrangement coupled with the atleast one pressurized storage tank, the at least one control arrangementcomprising: at least a first pressure sensor; at least a second pressuresensor; circuitry for determining a comparative pressure between thefirst pressure sensor and the second pressure sensor; at least onegyroscope; circuitry for determining an orientation at least partiallybased on a reading of the at least one gyroscope; and circuitry foradjusting a flow of a gas at least partially based on the comparativepressure and the orientation of the buoyancy control system, wherein theadjusting the flow of the gas alters the volume of gas in the pluralityof buoyancy tanks.